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Author

Xie, Mingshi

Date of Issue

2016

School

School of Chemical and Biomedical Engineering

Abstract

The research of this thesis is to develop copper (Cu) based materials with various strategies for CO2 electroreduction towards hydrocarbons. The generation of hydrocarbons is enhanced through taking advantages of modifiers as well as supports.
Firstly, we developed a general amino acid modification approach on Cu electrodes for selective electroreduction of CO2 towards hydrocarbons. Remarkable enhancement in hydrocarbon generation was achieved on these modified copper electrodes, regardless of the morphology of the Cu electrodes. A density functional theory (DFT) calculation revealed that the key intermediate CHO* was stabilized by interacting with –NH3+ of the adsorbed zwitterionic glycine. Our results suggested that amino acids and their derivatives were promising modifiers in improving the selectivity of hydrocarbons in CO2 electroreduction.
Secondly, Cu doped diamond-like carbon (DLC) film electrodes were synthesized under various potentials. Among all tested electrodes, Cu-DLC film prepared under -1200 V obtained the highest sp3 carbon content, and proved to have the best performance to generate hydrocarbons. DFT simulations indicate that the H atom adsorbed on diamond would be a better source for direct hydrogenation of adsorbed CO, compared to shuttling water as well as H adsorbed on Cu. The results showed that DLC is a good co-catalyst to help Cu producing more hydrocarbons.
Thirdly, a Cu doped carbon aerogel was prepared through carbonization of phenolic resin precursor. The Cu-carbon aerogel had an extremely high Cu loading of 25.8%, with large surface area. All these properties brought about improvements in FE of hydrocarbons as well as decrease of overpotential.
Cu-based composite materials are proved to be promising towards CO2 electroreduction. The strategy could be expanded to other types of materials, like metal-organic framework compounds, intermetallics as well as other chemically modified materials.